An increasing cutoff exponent \(\alpha _c\)  suppresses the power in the SGWB at LISA to PTA/THEIA frequencies. In the most extreme case, the bump around \(f\sim 10^{-5}\)  Hz is completely erased, and the SGWB in the LISA sensitivity band, which can be well described by a broken power-law, may be confused with signals coming from GW production in phase transitions (see e.g. [1]}).
